Photo Credit: Tyler Rooke

West Side

Today: Mostly sunny. Highs 80 to 88. Southeast winds up to 10 mph shifting to the southwest in the afternoon. Gusts up to 30 mph.

Tonight: Mostly clear. Lows 68 to 75. Northeast winds up to 15 mph.

Thursday: Sunny. Highs 81 to 88. East winds 10 to 15 mph.

South Side

Today: Sunny. Highs around 88. North winds up to 15 mph shifting to the southwest in the afternoon.

Tonight: Mostly clear. Lows 65 to 75. Northwest winds up to 15 mph shifting to the north after midnight.

Thursday: Sunny. Highs around 88. North winds 10 to 15 mph.

North Shore

Today: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 87 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 68 to 73 near the shore to 48 to 54 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 86 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Central Maui

Today: Mostly sunny. Highs 84 to 90. Southeast winds up to 10 mph increasing to 10 to 15 mph in the afternoon.

Tonight: Mostly clear. Lows 65 to 71. East winds up to 15 mph.

Thursday: Sunny. Highs 83 to 90. Northeast winds 10 to 15 mph.

Upcountry

Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 65 at the visitor center to around 60 at the summit. Southeast winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly clear. Breezy. Scattered showers in the evening. Lows around 49 at the visitor center to around 47 at the summit. East winds up to 15 mph increasing to 10 to 20 mph after midnight. Chance of rain 40 percent.

Thursday: Sunny and breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 64 at the visitor center to around 60 at the summit. East winds 10 to 20 mph. Chance of rain 40 percent.

East Maui

Today: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 87 near the shore to around 69 near 5000 feet. East winds up to 20 mph. Chance of rain 50 percent.

Tonight: Partly cloudy. Breezy. Scattered showers in the evening, then isolated showers after midnight. Lows 68 to 73 near the shore to 48 to 54 near 5000 feet. Southeast winds up to 20 mph. Chance of rain 50 percent.

Thursday: Mostly sunny. Breezy. Isolated showers in the morning, then scattered showers in the afternoon. Highs 78 to 86 near the shore to around 68 near 5000 feet. East winds 10 to 20 mph. Chance of rain 50 percent.

Lanai City

Today: Mostly sunny. Highs 74 to 82. Northeast winds 10 to 15 mph shifting to the west in the afternoon.

Tonight: Mostly clear. Lows 63 to 68. Southeast winds up to 10 mph in the evening becoming light.

Thursday: Sunny. Highs 74 to 82. Light winds.

Kaunakakai

Today: Mostly sunny with isolated showers. Highs 71 to 89. East winds up to 15 mph. Chance of rain 20 percent.

Tonight: Mostly clear. Lows 58 to 74. East winds up to 15 mph.

Thursday: Sunny. Highs 71 to 90. East winds 10 to 15 mph.

Detailed Forecast

Synopsis

The combination of a weakening subtropical ridge to our north, and a gale low well to our northwest, will keep southeast flow blowing over the islands for the next couple of days. Relatively dry air over the islands will keep showers fairly sparse. A few showers are expected over mainly windward and mauka areas, favoring the night and morning hours. Afternoon clouds and perhaps a shower or two will affect some interior and leeward areas as well. Trades will rebuild over the islands about Friday as a new, strong high pushes far north of us. The trades may turn a a bit more wet and breezy this weekend as additonal moisture and instability reach the islands.

Discussion

A vertically stacked gale low is located 550 mi NW of Kauai, moving S about 15 mph and slowing. Mid-level height falls associated with this feature, interacting with the remnant moisture associated with an diffuse, old frontal boundary over the northern main islands, led to an increase in shower coverage overnight. However, aside from windward Kauai, most of these showers have stayed N of the main islands or in the downwind convergence zones brushing the leeward coastal waters. The low level flow has veered to ESE as a result of this gale low and a weakening subtropical ridge far to our N. This is putting the smaller islands partly in the wind shadow of the higher terrain of Maui and the Big Island. Thus, light winds have led to overnight land breezes in many areas.
The convection-allowing models are continuing to show some possibility for downwind convergence-zone clouds and showers to get pulled up over Kauai and Oahu today, in addition to the possibility of a shower or two developing over interior or leeward sections this afternoon as well. Mid-level height falls continuing over the state today will be working against drier air pushing in south of the remnant frontal boundary, so any showers don't seem like they'd amount to much.
Not a lot of change is expected for the next few days with gentle to locally breezy E to SE flow in some exposed windward areas, and the pocket of relatively dry air over the state. This should lead to a hybrid pattern with a few showers over windward areas mainly nights and mornings, but also can't completely rule out a brief afternoon shower or two over a couple of interior and leeward spots which will remain shadowed from the ESE flow.
The gale low will weaken and start to move away on Thu, so that by Friday the flow around the islands will gradually back around to trades from E to W, locally breezy near the Big Island. Cyclonic flow developing aloft early next week could turn the trades somewhat wet over the weekend, although the models are in some disagreement about how much moisture and instability will be available.
The models seem to be in better agreement, though, about a cold front, accompanied by weak mid-level shortwave energy, reinforcing the wet trades Monday night, but this is still far out in time. Also, a high pressure area emerging off the Asian continent on Wed will slide across the N Pacific and strengthen as it does so. The high remains quite strong, near 1040 mb, as it begins to push southward far N of Hawaii early next week. This is very far out in time, but if the deterministic models are correct, could see advisory level trade wind speeds in some areas early next week.

Aviation

Expect moderate to locally breezy winds in today with winds blowing from an east to southeast direction, as a low pressure system sets up northwest of the Hawaii Region and the high pressure ridge shifts northward. Passing showers remain in the short range forecast, with clouds and showers favoring eastern and southeastern slopes of all islands.
AIRMET Sierra remains in effect for mountain obscurations along north through east sections of Kauai, Oahu, Molokai and Maui. This AIRMET will diminish a few hours after sunrise.
AIRMET Tango remains in effect for tempo moderate turbulence over and immediately south through west of all island mountains below 100. This AIRMET will diminish later this morning as wind speeds weaken.

Marine

Fresh to strong southeast winds will persist through Thursday over most windward waters and near the coasts where terrain-induced accelerations are typical with southeast winds. For the Kauai and Oahu waters, expect light to moderate southeast winds through this time, especially over the leeward waters as low pressure lingers northwest of the state. Winds will shift out of a more typical easterly trade wind direction and become strong over most waters this weekend through early next week as strong high pressure builds north of the state and the low weakens and shifts away from the region.
Surf along east facing shores will remain rough through the weekend due to the locally strong east-southeast winds and the fresh trades upstream across the eastern Pacific. Heights may approach advisory levels early next week if the strong winds materialize.
Surf along north and west facing shores will ease today, then pick up Thursday through the weekend as overlapping small, medium period, north-northwest swells arrive and move through.
Surf along south facing shores will remain small through the weekend with mainly a mix of short-period southeast energy and small background south swells moving through.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Thursday for Maui County Windward Waters, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

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Data Courtesy of NOAA.gov